Document Type

Article

Publication Date

8-1-1998

Department

Chemistry and Biochemistry

Abstract

Magnetically induced Freedericksz measurements were performed in the nematic liquid crystal phase to extract the elastic constants of a terminal-lateral-lateral-terminal trimer, i.e., a trimer in which the connections to the first and third mesogens are at the end of the mesogen and both attachments to the central mesogen are lateral. Polymeric liquid crystals based on this unit have negative Poisson ratios. Additionally, electric field Kerr measurements were performed in the isotropic phase to extract the orientational susceptibility. The elastic constants were found to be similar to values obtained for typical monomers, albeit with a slightly enhanced ratio K-33/K-11 and reduced ratio K-11/K-22 especially near the transition temperature. The temperature dependence of the susceptibility was found to deviate significantly from that of typical monomers. The observed behavior is discussed in terms of coupled order parameters representing the terminal and core mesogens of the molecule.